In a radio communication system, Coordinated Multi-Point (CoMP) transmission is a technology for improving overall performance of a cell and performance of users at the edge of the cell. Downlink CoMP transmission is a technology for multiple geographically distributed transmitters to jointly send data to a User Equipment (UE). In a CoMP system, network nodes include an evolved NodeB (eNodeB) and several Access Points (APs). An AP is a node that includes at least a radio frequency transceiver, and one or more antenna units can be configured on the AP. Multiple APs are geographically distributed and connected to the eNodeB, and can coordinate to transmit or receive data from the UE. The cooperative APs may be connected with a same eNodeB or different eNodeBs. In a CoMP system, multiple cooperative cells/APs send a same signal to the UE jointly, which enhances the power of the UE for receiving the signal and improves the performance of the UEs at the edge of the cells/APs. However, to receive signals from multiple cooperative cells/APs effectively, the UE needs to estimate the channel value between the UE and the cooperative cells/APs accurately.
In a Long Term Evolution (LTE) system, a reference signal pattern is put forward. The reference signal pattern includes common reference signals and dedicated reference signals. The common reference signals always exist, and are bound to a cell identity (ID); and the dedicated reference signals are bound to a UE ID and a cell ID.
In the conventional art, dedicated pilot frequencies are generally used to implement CoMP applications. In this way, the CoMP system is well compatible with the LTE system, without any extra signaling overhead. However, if the reference signal pattern provided by the LTE system is applied to the CoMP system, when multiple cooperative cells/APs serve a UE jointly, the reference signal interferes with the data signal reciprocally for every two cooperative cells/APs. Consequently, the UE is unable to estimate the channel value between the UE and the cooperative cells/APs accurately, which affects the performance of the UE seriously.